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Abstract:

A semiconductor module includes a semiconductor having a semiconductor
substrate, a first electrode formed on one surface of the semiconductor
substrate, and a second electrode formed on an opposite surface of the
semiconductor substrate. A first conductive member is in contact with the
first electrode. A second conductive member is in contact with the second
electrode. A third conductive member is in contact with the second
conductive member and extends along the first conductive member. An
insulating member provides insulation between the first conductive member
and the third conductive member. The third conductive member is fixed to
the first conductive member and the second conductive member by being
sandwiched between the first conductive member and the second conductive
member. The semiconductor device is fixed to the first conductive member
and the second conductive member by being sandwiched between the first
conductive member and the second conductive member.

Claims:

1. A semiconductor module, comprising: a semiconductor device comprising:
a semiconductor substrate, a first electrode formed on one surface of the
semiconductor substrate, and a second electrode formed on a surface of
the semiconductor substrate opposite to the one surface; a first
conductive member being in contact with the first electrode; a second
conductive member being in contact with the second electrode; a third
conductive member being in contact with the second conductive member and
extending along the first conductive member; and an insulating member
insulating between the first conductive member and the third conductive
member, wherein the third conductive member is fixed to the first
conductive member and the second conductive member by being sandwiched
between the first conductive member and the second conductive member, and
the semiconductor device is fixed to the first conductive member and the
second conductive member by being sandwiched between the first conductive
member and the second conductive member.

2. A semiconductor module of claim 1, further comprising a cylinder
formed of an insulator, encompassing the semiconductor device, fixed to
the first conductive member, and on an outer peripheral surface of which
a first thread groove is formed; wherein a second thread groove is formed
on the second conductive member, and the second conductive member is
fixed to the cylinder by an engagement of the first thread groove and the
second thread groove.

3. A semiconductor module of claim 2, wherein a first engaging portion
including at least one of a concavity or a convexity is formed on the
outer peripheral surface of the cylinder, the third conductive member
comprises a penetrating hole, a second engaging portion including at
least one of a concavity or a convexity is formed on an inner surface of
the penetrating hole, and the cylinder is inserted into the penetrating
hole of the third conductive member in a state where the first engaging
portion engages with the second engaging portion.

4. A semiconductor module of claim 1, the semiconductor device further
comprising a third electrode formed on the one surface of the
semiconductor substrate, and through which a smaller current than in the
first electrode and the second electrode flows, and the semiconductor
module further comprising a wiring member connected to the third
electrode and penetrating the first conductive member in a state of being
insulated from the first conductive member.

5. A semiconductor module of claim 4, wherein a concave portion is formed
on a back surface of the first conductive member which is a surface
opposite to a front surface of the first conductive member being in
contact with the first electrode, the wiring member penetrates the first
conductive member at a position at which the concave portion is formed
and extends along a bottom surface of the concave portion within the
concave portion, and the wiring member within the concave portion is
covered with an insulator.

6. A semiconductor module of claim 5, wherein a part of the back surface
of the first conductive member on which the concave portion is not formed
and a surface of the insulator within the concave portion form a
consecutive flat plane.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a Continuation of International Application No.
PCT/JP2011/073563 filed on Oct. 13, 2011, the disclosure of which is
hereby incorporated by reference herein in its entirety.

TECHNICAL FIELD

[0002] The technique disclosed in the present description relates to a
semiconductor module.

BACKGROUND ART

[0003] When a semiconductor device generates heat, the semiconductor
device and peripheral members thereof (solder, wiring, and the like)
thermally expand. Due to differences in coefficients of thermal expansion
among the respective members, stress acts on the semiconductor device.
Such stress reduces semiconductor device life.

SUMMARY

[0004] In order to reduce the aforementioned stress, connection of a
semiconductor device to wiring that does not involve joining with a
brazing material such as solder has been under consideration. For
example, Japanese Patent Application Laid-open No. H9-252067
(hereinafter, referred to as a patent document 1) discloses a
semiconductor module in which a semiconductor device and respective
electrode plates are laminated and pressurized in order to connect the
semiconductor device and the respective electrode plates to each other.
However, with this semiconductor module, a positive plate is arranged on
a lower surface of the semiconductor module and a negative plate is
arranged on an upper surface of the semiconductor module. Therefore, when
installing the semiconductor module to equipment, wirings must be
respectively connected to an upper surface side (in other words, a
negative plate side) of the semiconductor module and to a lower surface
side (in other words, a positive plate side) of the semiconductor module.
In other words, complicated wiring is required to install the
semiconductor module to the equipment. In consideration thereof, the
present description provides a semiconductor module that can be installed
to equipment using simpler wiring.

[0005] A semiconductor module disclosed in the present description
includes a semiconductor device, a first conductive member, a second
conductive member, a third conductive member, and an insulating member.
The semiconductor device includes a semiconductor substrate, a first
electrode formed on one surface of the semiconductor substrate, and a
second electrode formed on a surface of the semiconductor substrate
opposite to the one surface. The first conductive member is in contact
with the first electrode. The second conductive member is in contact with
the second electrode. The third conductive member is in contact with the
second conductive member and extends along the first conductive member.
The insulating member provides insulation between the first conductive
member and the third conductive member. The third conductive member is
fixed to the first conductive member and the second conductive member by
being sandwiched between the first conductive member and the second
conductive member. The semiconductor device is fixed to the first
conductive member and the second conductive member by being sandwiched
between the first conductive member and the second conductive member.

[0006] In this semiconductor module, the semiconductor device is fixed to
the first conductive member and the second conductive member by being
sandwiched between the first conductive member and the second conductive
member. In other words, the semiconductor device is fixed by pressure.
Since this semiconductor module does not use joining by a brazing
material, stress is less likely to be applied to the semiconductor device
when heat is being generated by the semiconductor device. The first
conductive member is electrically connected to the first electrode of the
semiconductor device. In addition, the third conductive member is
electrically connected to the second electrode of the semiconductor
device via the second conductive member. The third conductive member
extends along the first conductive member. Therefore, when installing
this semiconductor module to equipment, wirings to the third conductive
member and the first conductive member can be provided with ease.

BRIEF DESCRIPTION OF DRAWINGS

[0007]FIG. 1 is a schematic cross-sectional view of a semiconductor
module 10 according to a first embodiment;

[0008]FIG. 2 is a cross-sectional view of the semiconductor module 10
taken along line II-II in FIG. 1;

[0009]FIG. 3 is a cross-sectional view of the semiconductor module 10
taken along line III-III in FIG. 1;

[0010]FIG. 4 is a schematic cross-sectional view of a semiconductor
module according to a first modification;

[0011]FIG. 5 is a schematic cross-sectional view of a semiconductor
module according to a second modification;

[0012]FIG. 6 is a schematic cross-sectional view showing a method of
assembling a semiconductor module according to a third modification;

[0013]FIG. 7 is a schematic cross-sectional view showing a method of
assembling a semiconductor module according to a fourth modification;

[0014]FIG. 8 is a schematic cross-sectional view of a semiconductor
module 100 according to a second embodiment;

[0015]FIG. 9 is an enlarged cross-sectional view of a concave portion
140; and

[0016]FIG. 10 is a schematic cross-sectional view of a semiconductor
module 200 according to a third embodiment.

DESCRIPTION OF EMBODIMENTS

[0017] The semiconductor module described in this specification may
further include a cylinder. The cylinder may be formed of an insulator,
encompassing the semiconductor device, and fixed to the first conductive
member. A first thread groove may be formed on an outer peripheral
surface of the cylinder. In addition, a second thread groove may be
formed on the second conductive member, and the second conductive member
may be fixed to the cylinder by an engagement of the second thread groove
with the first thread groove.

[0018] With this semiconductor module, the second conductive member can be
fixed to the cylinder by rotating the second conductive member and
causing the second thread groove to engage with the first thread groove.
In addition, according to such a configuration, by rotating the second
conductive member, the semiconductor device and the third conductive
member that are located between the second conductive member and the
first conductive member can be pressurized and fixed. In other words, by
assembling the second conductive member to the cylinder, the second
conductive member, the third conductive member, the first conductive
member, and the semiconductor device can be fixed to each other.
Consequently, this semiconductor module can be assembled with ease.
Furthermore, since the third conductive member is a member that is
separated from the second conductive member, the second conductive member
can be rotated independently from the third conductive member. Therefore,
the third conductive member can be readily positioned with respect to the
first conductive member.

[0019] In the semiconductor module described in this specification, a
first engaging portion configured of a concavity or a convexity may be
formed on the outer peripheral surface of the cylinder. The third
conductive member may include a penetrating hole, a second engaging
portion configured of a concavity or a convexity may be formed on an
inner surface of the penetrating hole, and the cylinder may be inserted
into the penetrating hole of the third conductive member in a state where
the first engaging portion engages with the second engaging portion.

[0020] According to such a configuration, when rotating the second
conductive member, the third conductive member can be prevented from
relatively rotating with respect to the first conductive member.
Therefore, the third conductive member can be reliably positioned with
respect to the first conductive member.

[0021] In the semiconductor module described in this specification, a
third electrode, through which a smaller current than in the first
electrode and the second electrode flows, may be further formed on the
one surface of the semiconductor substrate. In addition, the
semiconductor module may further include a wiring member connected to the
third electrode and penetrating the first conductive member in a state of
being insulated from the first conductive member.

[0022] According to such a configuration, the wiring member connected to
the third electrode can be extended to a side of the first conductive
member. Therefore, a wiring to the third electrode can be provided at a
position near the first conductive member.

[0023] In the semiconductor module described in this specification, a
concave portion may be formed on a back surface of the first conductive
member which is a surface opposite to a front surface of the first
conductive member being in contact with the first electrode. The wiring
member may penetrate the first conductive member at a position at which
the concave portion is formed and extends along a bottom surface of the
concave portion within the concave portion. The wiring member within the
concave portion may be covered by an insulator.

[0024] According to such a configuration, the wiring member does not
protrude from the back surface of the first conductive member. The back
surface of the first conductive member can be readily brought into close
contact with other equipment. Therefore, according to the present
configuration, the semiconductor module can be assembled to the equipment
with ease.

[0025] In the semiconductor module described in this specification, a part
of the back surface of the first conductive member on which the concave
portion is not formed and a surface of the insulator within the concave
portion may form a consecutive flat plane.

[0026] According to such a configuration, the semiconductor module can be
assembled to equipment with greater ease.

First Embodiment

[0027] A semiconductor module 10 shown in FIG. 1 is an assembly in which a
semiconductor device 20 is housed in a case 40 and a cover 50.

[0028] The case 40 includes an electrode plate 40a formed of metal and an
insulating portion 40b formed of an insulator. The electrode plate 40a is
formed in an approximately planar shape. The insulating portion 40b is
formed of a high-strength engineering plastic such as a phenolic resin.
The insulating portion 40b is fixed on the electrode plate 40a. As shown
in FIGS. 1 to 3, the insulating portion 40b includes a cylindrical
portion 40c and a flange portion 40d. The cylindrical portion 40c is
formed in a cylindrical shape with a central axis extending perpendicular
to the electrode plate 40a. A thread groove 40f is formed on an outer
peripheral surface of the cylindrical portion 40c. A convex portion 40g
is formed on a lower side of the thread groove 40f. As shown in FIG. 3,
the convex portion 40g is a portion that partially protrudes from an
outer peripheral surface of the cylindrical portion 40c. The flange
portion 40d is a disk-like portion with a radius that is lager than the
outer peripheral surface of the cylindrical portion 40c. The flange
portion 40d is formed on a lower side of the convex portion 40g. A part
of the electrode plate 40a constitutes an extending portion 40h that
extends outward from a portion at which the insulating portion 40b is
fixed.

[0029] A metal plate 84, the semiconductor device 20, a metal plate 82,
and pins 90 are installed on the electrode plate 40a at a position inside
the cylindrical portion 40c.

[0030] The metal plate 84 is installed on the electrode plate 40a. The
metal plate 84 is constructed of a relatively soft metal such as tin.

[0031] The semiconductor device 20 is installed on the metal plate 84. The
semiconductor device 20 includes a semiconductor substrate 24 constructed
of SIC. A MOSFET is formed in the semiconductor substrate 24. A source
electrode 26 of the MOSFET and a plurality of gate electrodes 28 of the
MOSFET are formed on a lower surface of the semiconductor substrate 24.
Dotted lines 26 and 28 in FIG. 2 indicate positions of the source
electrode 26 and the gate electrodes 28 on the lower surface of the
semiconductor substrate 24. As shown in FIG. 2, the semiconductor
substrate 24 has a square shape. The plurality of gate electrodes 28 is
arranged along one side of the semiconductor substrate 24. As shown in
FIG. 1, a drain electrode 22 of the MOSFET is formed on an upper surface
of the semiconductor substrate 24. The semiconductor device 20 is
installed on the metal plate 84 so that the source electrode 26 comes
into contact with the metal plate 84. The respective gate electrodes 28
are not in contact with the metal plate 84. A current smaller than
currents that flow through the source electrode 26 and the drain
electrode 22 flows through each gate electrodes 28.

[0032] The metal plate 82 is installed on the semiconductor device 20. The
metal plate 82 is formed of a relatively soft metal such as tin. The
metal plate 82 is in contact with the drain electrode 22 of the
semiconductor device 20.

[0033] A through hole 94 that penetrates the electrode plate 40a of the
case 40 from an upper surface to a lower surface of the electrode plate
40a is formed in the electrode plate 40a at a position opposing the gate
electrodes 28 of the semiconductor device 20. The through hole 94 extends
along a direction in which the plurality of gate electrodes 28 is
arranged. Specifically, a single through hole 94 having an approximately
rectangular shape in a plan view is formed in the electrode plate 40a so
as to oppose all of the gate electrodes 28. An insulating member 92 is
fixed inside the through hole 94. The insulating member 92 is constructed
by a resin material such as polyphenylene sulfide (PPS). The through hole
94 is blocked by the insulating member 92. Metallic pins 90 are fixed to
the insulating member 92 at a location that opposes the gate electrodes
28. As shown in FIG. 3, a pin 90 is fixed to each position that opposes
each gate electrode 28. Each pin 90 penetrates the insulating member 92.
Consequently, an upper end of each pin 90 is positioned on an upper side
of the electrode plate 40a, and a lower end of each pin 90 is positioned
on a lower side of the electrode plate 40a. A portion 90a of each pin 90
on the upper side of the electrode plate 40a is a spring portion that
deforms elastically. Each spring portion 90a is in contact with a
corresponding gate electrode 28 in a bent state. Each pin 90 is insulated
from the electrode plate 40a of the case 40 by the insulating member 92.

[0034] The cover 50 is constructed of metal. An insulation coating is
applied to an outer surface of the cover 50. The cover 50 includes a side
wall portion 50b having a cylindrical shape and a flat plate portion 50a
that blocks one end of a central hole of the side wall portion 50b. In
other words, the cover 50 is shaped like a cup. A thread groove 50c is
formed on an inner peripheral surface of the side wall portion 50b. The
thread groove 50c of the cover 50 engages with the thread groove 40f of
the case 40. In other words, the cover 50 is fastened to the case 40
using the thread grooves 40f and 50c. A lower surface of the flat plate
portion 50a of the cover 50 is in contact with the insulating plate 82.
More specifically, the flat plate portion 50a of the cover 50 and the
electrode plate 40a of the case 40 sandwich a laminated body constituted
by the metal plate 84, the semiconductor device 20, and the metal plate
82. The cover 50 is fastened at a high torque to the case 40. As a
result, the laminated body is pressurized by the flat plate portion 50a
and the electrode plate 40a. Due to the pressure, respective members
constituting the laminated body are fixed. Moreover, a contact portion of
the electrode plate 40a of the case 40 and the metal plate 84, a contact
portion of the metal plate 84 and the source electrode 26 of the
semiconductor device 20, a contact portion of the drain electrode 22 of
the semiconductor device 20 and the metal plate 82, a contact portion of
the metal plate 82 and the flat plate portion 50a of the cover 50, and a
contact portion of the pin 90 and the gate electrode 28 of the
semiconductor device 20 are not joined by a brazing material such as
solder. Therefore, if the cover 50 is detached from the case 40, the
respective members of the laminated body can be separated from each
other.

[0035] In addition, the semiconductor module 10 includes a bus bar 30. The
bus bar 30 is formed of metal. The bus bar 30 includes a ring portion 30a
and a plate portion 30b that extend outward from the ring portion 30a.
The ring portion 30a is thinner than the plate portion 30b. As shown in
FIG. 3, a concave portion 30d is formed on an inner surface of a central
hole 30c of the ring portion 30a. The cylindrical portion 40c of the case
40 is inserted into the central hole 30c of the ring portion 30a. The
concave portion 30d of the ring portion 30a is engaged with the convex
portion 40g of the cylindrical portion 40c. The plate portion 30b extends
approximately parallel to the extending portion 40h of the electrode
plate 40a at an interval from the extending portion 40h. An upper surface
of the ring portion 30a is in contact with a lower end of a side wall
portion 50b of the cover 50. A lower surface of the ring portion 30a is
in contact with the flange portion 40d of the case 40. The ring portion
30a is sandwiched from above and below by the cover 50 and the case 40.
As described above, the cover 50 is fastened at a high torque to the case
40. Therefore, the ring portion 30a is pressurized by the cover 50 and
the case 40. Due to the pressure, the bus bar 30 is fixed to the cover 50
and the case 40. The bus bar 30 is insulated from the electrode plate 40a
by the flange portion 40d.

[0036] An insulating sheet 70 is installed on an upper surface of the flat
plate portion 50a of the cover 50. A cooler 60 is installed on an upper
surface of the insulating sheet 70. The cooler 60 is a liquid
circulation-type cooler. Moreover, grease is applied to a contact portion
of the cover 50 and the insulating sheet 70 and to a contact portion of
the insulating sheet 70 and the cooler 60. Consequently, thermal
resistance between the cooler 60 and the cover 50 is reduced.

[0037] As described above, in the semiconductor module 10, a wiring to the
source electrode 26 positioned on a lower surface side of the
semiconductor substrate 24 is constituted by the electrode plate 40a of
the case 40. In addition, a wiring to a drain electrode 22 positioned on
an upper surface side of the semiconductor substrate 24 is constituted by
the bus bar 30. The bus bar 30 is connected to a side surface of the case
40 and extends approximately parallel to the electrode plate 40a. In this
manner, since the electrode plate 40a and the bus bar 30 are arranged
close to each other, external wirings thereto can be readily installed.
Furthermore, by arranging the electrode plate 40a and the bus bar 30
close to and approximately parallel to each other, an inductance between
the electrode plate 40a and the bus bar 30 can be reduced. In particular,
since the bus bar 30 is an approximately flat plate-like member, an
interval between the bus bar 30 and the electrode plate 40a can be
accurately controlled by a thickness of the flange portion 40d.
Therefore, the interval between the bus bar 30 and the electrode plate
40a can be further reduced. As a result, in the semiconductor module 10,
the inductance between the electrode plate 40a and the bus bar 30 is
extremely low.

[0038] Furthermore, the pins 90 that are wirings to the gate electrodes 28
penetrate the electrode plate 40a of the case 40 and extend to the lower
side of the electrode plate 40a. As a result, wirings are not installed
on an upper surface of the cover 50. Since no wirings are located on the
upper surface of the cover 50, an entirety of the upper surface of the
cover 50 can be connected to a cooler 60 via an insulating sheet 70.
Consequently, the semiconductor device 20 can be cooled by the cooler 60
in a preferable manner.

[0039] Furthermore, in the semiconductor module 10, the semiconductor
device 20 is fixed by pressure, and the semiconductor device 20 and the
peripheral members thereof are not joined with each other by brazing or
the like. Therefore, when the semiconductor device 20 and the peripheral
members thereof thermally expand due to heat generated by the
semiconductor device 20, stress is less likely to act on the
semiconductor device 20. Consequently, the semiconductor module 10 has a
long life.

[0040] In addition, in the semiconductor module 10, the cover 50 itself
functions as a part of the wiring to the drain electrode 22. Therefore,
by simply bringing the bus bar 30 into contact with the cover 50, the bus
bar 30 and the drain electrode 22 can be electrically connected to each
other. In a hypothetical case of a structure in which the bus bar
penetrates the cover 50 and the electrode plate 40a and then connects to
the drain electrode 22, penetrating holes must be formed at the cover 50
and the electrode plate 40a, a structure of a semiconductor module must
becomes more complex, and a size of the semiconductor module must be
increased in order to secure space for the penetrating holes. In
addition, since a length of wirings in the semiconductor module
increases, an inductance of the wirings also increases. Such problems do
not occur with the semiconductor module 10 according to the first
embodiment. As a result, the semiconductor module 10 with a small size
and a low inductance can be provided.

[0041] Next, a method of manufacturing the semiconductor module 10 will be
described. First, the case 40 is prepared, and the metal plate 84 is
placed on the electrode plate 40a inside the cylindrical portion 40c. A
component that integrates the plurality of pins 90, and the insulating
member 92 is then installed in the penetrating hole 94 of the electrode
plate 40a. Next, the semiconductor device 20 is placed on the metal plate
84. In doing so, the source electrode 26 is brought into contact with the
metal plate 84, and the respective gate electrodes 28 are brought into
contact with corresponding pins 90. The metal plate 82 is then placed on
the semiconductor device 20. Next, the bus bar 30 is installed on the
case 40 so that the ring portion 30a is placed on the flange portion 40d.
Then, by causing the thread groove 50c of the cover 50 to engage with the
thread groove 40f of the case 40, the cover 50 is fixed to the case 40.
When the cover 50 is moved downward by rotating the cover 50 around a
central axis thereof, the flat plate portion 50a of the cover 50 comes
into contact with the metal plate 82. In addition, a lower end of the
side wall portion 50b of the cover 50 comes into contact with the ring
portion 30a of the bus bar 30. By further rotating the cover 50 from this
state, the flat plate portion 50a of the cover 50 pressurizes the metal
plate 82 toward the semiconductor device 20. More specifically, a
laminated body sandwiched between the flat plate portion 50a of the cover
50 and the electrode plate 40a of the case 40 (in other words, the metal
plate 84, the semiconductor device 20, and the metal plate 82) is
pressurized in a direction of lamination of the laminated body.
Accordingly, respective members of the laminated body are fixed to the
case 40 and to the cover 50. At the same time, the side wall portion 50b
of the cover 50 pressurizes the ring portion 30a of the bus bar 30 toward
the flange portion 40d. In other words, the ring portion 30a sandwiched
between the side wall portion 50b and the flange portion 40d is
pressurized. Accordingly, the bus bar 30 is fixed to the case 40 and to
the cover 50.

[0042] Moreover, the metal plate 84 is softer than the source electrode 26
and the electrode plate 40a of the case 40 that are adjacent to the metal
plate 84. Therefore, when the laminated body is pressurized, an upper
surface of the metal plate 84 plastically deforms so as to conform to a
surface shape of the source electrode 26 and the metal plate 84 comes
into close contact with the source electrode 26. In a similar manner,
when the laminated body is pressurized, a lower surface of the metal
plate 84 plastically deforms so as to conform to a surface shape of the
electrode plate 40a and the metal plate 84 comes into close contact with
the electrode plate 40a. As a result, the source electrode 26 and the
electrode plate 40a are electrically connected with each other securely.

[0043] In addition, the metal plate 82 is softer than the drain electrode
22 and the cover 50 that are adjacent to the metal plate 82. Therefore,
when the laminated body is pressurized, a lower surface of the metal
plate 82 plastically deforms so as to conform to a surface shape of the
drain electrode 22 and the metal plate 82 comes into close contact with
the drain electrode 22. In a similar manner, when the laminated body is
pressurized, an upper surface of the metal plate 82 plastically deforms
so as to conform to a surface shape of the cover 50 and the metal plate
82 comes into close contact with the cover 50. As a result, the drain
electrode 22 and the cover 50 are electrically connected with each other
securely.

[0044] Furthermore, when the laminated body is pressurized, the spring
portions 90a of the pins 90 deflect. As a result, an appropriate pressure
is applied between the pins 90 and the gate electrodes 28 and the pins 90
and the gate electrodes 28 are electrically connected with each other
securely.

[0045] Once the cover 50 is fixed to the case 40, the cooler 60 is
attached to the cover 50 via the insulating sheet 70, whereby the
semiconductor module 10 shown in FIG. 1 is completed.

[0046] In the semiconductor module 10, no wiring to the semiconductor
device 20 penetrates the cover 50. Therefore, the cover 50 can be freely
rotated during assembly. As a result, the cover 50 can be attached to the
case 40 by causing the thread groove 40f and the thread groove 50c to
engage each other. In addition, because of this screw structure, the
cover 50 can pressurize and fix the laminated body and the bus bar 30.
Consequently, the semiconductor module 10 can be assembled with ease.

[0047] Furthermore, in the semiconductor module 10, the bus bar 30 is
constituted by a component that differs from the cover 50. Furthermore,
upon assembly of the semiconductor module 10, when the cylindrical
portion 40c is inserted into the central hole 30c of the ring portion 30a
of the bus bar 30, the concave portion 30d of the bus bar 30 engages with
the convex portion 40g of the cylindrical portion 40c. Accordingly, the
bus bar 30 is no longer capable of relative rotation with respect to the
case 40. As a result, when rotating the cover 50 to fasten the cover 50
to the case 40, relative positions of the bus bar 30 and the case 40
remain unchanged. Accordingly, a displacement of the bus bar 30 and the
case 40 is prevented. Therefore, the bus bar 30 can be readily fixed to a
position opposing the extending portion 40h of the electrode plate 40a.

[0048] Moreover, the semiconductor module 10 according to the first
embodiment corresponds to respective components set forth in the claims
as follows. The electrode plate 40a of the case 40 and the metal plate 84
constitute a first conductive member according to the claims. The cover
50 and the metal plate 82 constitute a second conductive member according
to the claims. The bus bar 30 constitutes a third conductive member
according to the claims. The flange portion 40d of the case 40
constitutes an insulating member according to the claims. The cylindrical
portion 40c of the case 40 constitutes a cylinder according to the
claims.

[0049] In the first embodiment, the concave portion 30d is formed on the
bus bar 30 and the convex portion 40g is formed on the cylindrical
portion 40c, whereby the concave portion 30d and the convex portion 40g
engage with each other. Alternatively, a convex portion may be formed on
the bus bar 30 and a concave portion may be formed on the cylindrical
portion 40c, whereby the convex portion and the concave portion may
engage with each other.

[0050] In addition, while the semiconductor module 10 according to the
first embodiment includes the metal plate 84, alternatively, the metal
plate 84 may be absent and the source electrode 26 may come into direct
contact with the electrode plate 40a. Furthermore, while the
semiconductor module 10 according to the first embodiment includes the
metal plate 82, alternatively, the metal plate 82 may be absent and the
drain electrode 22 may come into direct contact with the case 40.

[0051] Next, a semiconductor module according to a modification of the
semiconductor module 10 according to the first embodiment will be
described. Moreover, in the following description of respective
semiconductor modules according to modifications, members configured
similarly to those of the first embodiment are denoted by the same
reference numbers as in the first embodiment.

[0052] In the first embodiment, the cover 50 is fixed to the cooler 60 via
the insulating sheet 70. Alternatively, an insulating film may be formed
on a surface of the cover 50 and the cover 50 may be fixed to the cooler
60 via the insulating film. Furthermore, as shown in FIG. 4, an
insulating cap 72 may be overlaid on the cover 50 and the cover 50 may be
fixed to the cooler 60 via the cap 72.

[0053] In addition, in the first embodiment, the flange portion 40d that
is integrated with the cylindrical portion 40c is arranged under the bus
bar 30. Alternatively, as shown in FIG. 5, an insulator 40i arranged
under the bus bar 30 may be separated from the cylindrical portion 40c.
In this case, the insulator 40i is a ring-like member and is arranged so
as to overlap the ring portion 30a of the bus bar 30. The insulator 40i
and the ring portion 30a are sandwiched between the case 40 and the cover
50 in a laminated state. The bus bar 30 and the insulator 40i are fixed
by being pressurized by the case 40 and the cover 50.

[0054] Alternatively, as shown in FIG. 6, a component 96 in which an
insulating layer 40j is formed on a lower surface of the bus bar 30 may
be prepared and installed on the electrode plate 40a. Even with such a
configuration, the bus bar 30 can be insulated from the electrode plate
40a.

[0055] Alternatively, as shown in FIG. 7, a flowable resin 98 containing
particles with a certain diameter may be applied on the electrode plate
40a, and the bus bar 30 may be arranged on the resin 98. Even in this
case, an interval between the bus bar 30 and the electrode plate 40a is
secured by the particles in the resin 98. The resin 98 may or may not be
hardened after installing the bus bar 30.

Second Embodiment

[0056] Next, a semiconductor module 100 according to a second embodiment
shown in FIG. 8 will be described. The semiconductor module 100 according
to the second embodiment shares the same configuration as the
semiconductor module 10 according to the first embodiment with the
exception of the electrode plate 40a and the pin 90. Moreover, in the
following description of the semiconductor module 100 according to the
second embodiment, members corresponding to the respective members
constituting the semiconductor module 10 according to the first
embodiment are denoted by the same reference numbers as in the first
embodiment.

[0057] In the semiconductor module 100 according to the second embodiment,
a concave portion 140 is formed on a lower surface of the electrode plate
40a. FIG. 9 is an enlarged cross-sectional view of a vicinity of the
concave portion 140. A bottom surface 140a of the concave portion 140 is
positioned on an upper side relative to a back surface 40e of the
electrode plate 40a other than the concave portion 140. A penetrating
hole 94 formed on the electrode plate 40a is opened to the bottom surface
140a of the concave portion 140. The pin 90 is bent within the concave
portion 140. The pin 90 within the concave portion 140 extends
approximately parallel to the bottom surface 140a of the concave portion
140. Two insulating members 142 and 144 are arranged within the concave
portion 140. The insulating member 142 is arranged between the pin 90 and
the electrode plate 40a and insulates the pin 90 from the electrode plate
40a. The insulating member 144 is arranged on a lower side of the pin 90.
A gap is formed between the insulating member 142 and the insulating
member 144, and the pin 90 extends along the gap. A surface 144a of the
insulating member 144 is a flat plane. The surface 144a of the insulating
member 144 is positioned at approximately a same height as the back
surface 40e of the electrode plate 40a other than the concave portion
140. As a result, a consecutive flat plane is formed by the surface 144a
and the back surface 40e.

[0058] An insulating sheet 170 is installed on a lower surface of the case
40 (in other words, the surface 144a and the back surface 40e). A cooler
160 is installed on a lower surface of the insulating sheet 170. With the
semiconductor module 100 according to the second embodiment, a
semiconductor device 20 can be cooled not only by an upper surface side
cooler 60 but also by the lower surface side cooler 160.

[0059] As described above, in the semiconductor module 100 according to
the second embodiment, the pin 90 penetrating the electrode plate 40a is
bent and housed within the concave portion 140. Since the pin 90 is a
wiring through which a small current flows, the pin 90 has a small
diameter. Therefore, the pin 90 can be bent easily and housed within the
concave portion 140 in a preferable manner. By housing the pin 90 within
the concave portion 140 as described above, the lower surface of the case
40 (the surface 144a and the back surface 40e) can be formed flat. Since
the lower surface of the case 40 is formed flat, an entirety of the lower
surface of the case 40 can be connected to the cooler 160 via the
insulating sheet 170. Consequently, the semiconductor device 20 can be
cooled by the cooler 160 in an efficient manner. With the semiconductor
module 100, a rise in temperature of the semiconductor device 20 can be
better suppressed using the two coolers 60 and 160.

[0060] Moreover, the semiconductor module 100 according to the second
embodiment can be assembled as follows. First, using the electrode plate
40a on which the concave portion 140 is formed, a same operation as in
the first embodiment is performed. The insulating member 142 is then
installed within the concave portion 140. Next, the pin 90 is bent. The
insulating member 144 is then installed within the concave portion 140 so
that the surface 144a of the insulating member 144 and the back surface
40e of the electrode plate 40a are flat. Subsequently, by mounting the
insulating sheet 170 and the cooler 160, the semiconductor module 100
shown in FIG. 8 is completed.

Third Embodiment

[0061] Next, a semiconductor module 200 according to a third embodiment
shown in FIG. 10 will be described. The semiconductor module 200
according to the third embodiment shares a same configuration as the
semiconductor module 10 according to the first embodiment with the
exception of the cover 50 and the case 40. Moreover, in the following
description of the semiconductor module 200 according to the third
embodiment, members corresponding to the respective members constituting
the semiconductor module 10 according to the first embodiment are denoted
by the same reference numbers as in the first embodiment.

[0062] In the semiconductor module 200 according to the third embodiment,
the case 40 does not include a cylindrical portion. In other words, the
case 40 is constituted by an electrode plate 40a and an insulator 40d (a
portion corresponding to the flange portion 40d according to the first
embodiment).

[0063] In the semiconductor module 200 according to the third embodiment,
a flange portion 50d is formed at a lower end of a side wall portion 50b
of the cover 50.

[0064] Formed on the flange portion 50d of the cover 50, the bus bar 30,
and the insulator 40d are penetrating holes 152 that penetrate the flange
portion 50d, the bus bar 30, and the insulator 40d. Although not shown,
the penetrating hole 152 is formed at three locations. In addition, screw
holes 154 are formed on the electrode plate 40a at three locations
corresponding to the penetrating holes 152.

[0065] Screws 162 are fastened to the screw holes 154 through the
penetrating holes 152. The cover 50 is fixed to the case 40 by three
screws 162. The metal plate 82, the semiconductor device 20, and the
metal plate 84 are fixed by being sandwiched between the cover 50 and the
case 40. In addition, the bus bar 30 is fixed by being sandwiched between
the cover 50 and the case 40. Moreover, the three screws 162 are formed
of an insulator. Therefore, the cover 50 is insulated from the electrode
plate 40a.

[0066] As described above, even with a configuration according to the
third embodiment, the semiconductor device 20 and the bus bar 30 can be
fixed by pressurization created by fastening the screws 162.

[0067] Moreover, while a MOSFET has been described as the semiconductor
devices according to the embodiments shown above, configurations of the
embodiments described above are applicable to various semiconductor
devices such as an IGBT and a diode.

[0068] In addition, in the embodiments described above, the pin 90 is a
wiring to the gate electrode 28. Alternatively, the pin 90 may be another
wiring. For example, the pin 90 may be wiring for detecting a current
that flows through the semiconductor device 20 (such as a wiring through
which flows a current having a certain ratio to a current flowing through
a source electrode 26) or a wiring for measuring a temperature of the
semiconductor device 20 (such as a wiring through which flows a current
that varies according to the temperature of the semiconductor device 20).

[0069] While preferred embodiments of the present disclosure have been
described using specific terms, such description is for illustrative
purposes only and is not intended to limit the scope of the following
claims. The techniques described in the claims include various
modifications and changes made to the specific embodiments illustrated
above. The technical elements described in this description or in the
drawings exhibit technical utility singly or in various combinations and
are not limited to the combinations recited in the claims as filed.
Moreover, the techniques illustrated in this description or in the
drawings simultaneously attain a plurality of purposes, and attaining one
of the purposes per se offers technical utility.